Wordnet 3.0
NOUN (1)
1.
immunity to a particular disease that is not innate but has been acquired during life;
immunity can be acquired by the development of antibodies after an attack of an infectious disease or by a pregnant mother passing antibodies through the placenta to a fetus or by vaccination;
WordNet (r) 3.0 (2006):
acquired immunity
n 1: immunity to a particular disease that is not innate but has
been acquired during life; immunity can be acquired by the
development of antibodies after an attack of an infectious
disease or by a pregnant mother passing antibodies through
the placenta to a fetus or by vaccination